Studies on the role of goat heart galectin-1 as a tool for detecting post-malignant changes in glycosylation pattern

Abstract

Galectins are mammalian lectins established to play a crucial role in the progression of various cancer types by the virtue of their differential expression in normal and cancerous cells. In the present study, goat heart galectin-1 (GHG-1) was purified and investigated for its potential role in the detection of post-malignant changes in glycosylation pattern. When exposed to superoxide radicals generated from a pyrogallol auto-oxidation system, GHG-1 treated erythrocyte suspension released higher amount of oxyhemoglobin than the unagglutinated erythrocytes. The extent of erythrocyte hemolysis was found to be directly proportional to concentrations of hypochlorous acid. GHG-1 was used to detect the change in the β-galactoside expression pattern in erythrocyte membrane from human donors suffering from prostate and breast cancer. No significant change was observed in the hemolysis of lectin agglutinated erythrocytes collected from pre-operated breast cancer patients, whereas significant increase was observed in normal healthy control and post-operated samples. Findings of this study proclaim GHG-1 as an important tool for the detection of post-malignant changes in glycosylation pattern.

Keywords: Cancer; GHG-1, goat heart galectin-1; Gal-1, galectin-1; Glycosylation; Goat heart galectin-1; HOCl; HOCl, hypochlorous acid; OxyHb, oxyhemoglobin; Oxyhemoglobin; Pyrogallol.

Figure 1

Effect of GHG-1 on pyrogallol induced free radical damage to erythrocyte membrane: OxyHb concentration was measured in the hemolysates of ‘a’: erythrocytes exposed to superoxide radicals in the absence of GHG-1, ‘b’: erythrocytes exposed to superoxide radicals in the presence of GHG-1 after 1 h, ‘c’: erythrocytes exposed to superoxide radicals in the presence of GHG-1 after 4 h. Samples were centrifuged and RBC lysates were analyzed at 540 nm. Values shown are the mean ± S.E.M obtained from three observations.

Figure 2

Effect of hypochlorous acid on GHG-1 induced hemolysis of trypsinized rabbit erythrocytes: an 8% trypsinized rabbit erythrocyte suspension (200 μl) treated with 100 μl GHG-1 (100 μg/ml) was incubated at varying concentrations of HOCl (50–350 μM). Samples were centrifuged and RBC lysates were analyzed at 540 nm.

Figure 3

Hemolysis of human erythrocytes collected from normal, pre-operated and post-operated breast cancer patients in the absence and presence of GHG-1: an 8% trypsinized rabbit erythrocyte suspension (200 μl) was prepared for normal, pre-operated and post-operated blood samples obtained from breast cancer patients, and treated in the presence and absence of GHG-1 (100 μg/ml). The degree of hemolysis was calculated by comparing with identical volume of erythrocytes mixed with distilled water which represented 100% lysis. Values shown are the mean ± S.E.M obtained from three observations.

Figure 4

Hemolysis of human erythrocytes collected from normal, pre-operated and post-operated prostate cancer patients in the absence and presence of GHG-1: An 8% trypsinized rabbit erythrocyte suspension (200 μl) was prepared for normal, pre-operated and post-operated blood samples obtained from prostate cancer patients, and treated in the presence and absence of GHG-1 (100 μg/ml). The degree of hemolysis was calculated by comparing with identical volume of erythrocytes mixed with distilled water which represented 100% lysis. Values shown are the mean ± S.E.M obtained from three observations.